well , it doesn't really make sense ...since w800 and w810 doesn't have the same platform , let alone K750 !!
in order to get ur phone back to life , u have 2 ways (CID depending ):
1-CID-36 ..look for K750_R1N035_CID36_FullRepairFlash.mbn file and flash it as main ...!
2-CID-49 you need to flash : k750_EROM_CID49.mbn .
then use any k750-cid-49 firmware/fs.
Hopefully , you manage to get it back alive !
Best Regards.